The overall objective of this project is to determine the molecular basis for the interaction of nerve and muscle. We have previously characterized the Band 1 protein, a murine nervous system specific cell surface antigen. Currently, efforts to determine whether Band 1 is a marker for a particular subclass of neurons center around analysis of activity in the cerebella of mice with characterized nervous system mutations. New antisera to Band 1 are being developed for histologic analysis of neural tissues. The search for additional neuron-specific cell surface components is continuing with the analysis of chick brain primary cultures which are greater than 95% neuronal. Cell surface components are identified by lactoperoxidase iodination and PDP/NaB3H4 labelling. Analagous cultures from rat or mouse brain currently contain unacceptably high levels of (putative) glial contamination which must be eliminated prior to cross-species comparisons of neuron cell surface components. Spinal cord cultures are being prepared in the same fashion for analysis of a population enriched in cholinergic cells.